Electrically-operated piano-player.



W- C. REED.

Patented Aug. 7, 1917..

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UNITED STATES PATENT OFFICE.

WALTER C. REED, OF DALTON, NIASSAGHUSETTS, ASSIGNOR TO THE TELELECTBIC COMI- PANY, OF PITTSFIELD, MASSACHUSETTS, A CORPORATION OF -MASSACHUSETTS.

, ELECTRICALLY-OPEBATED PIANO-PLAYER.

Specification of Letters Patent.

Patented A11 *7, 1917.

Application filed May 31, 1913.. Serial No. 770,819.

To all whom it may concern:

Be it known that I, WALTER C. REED, a citizen of the United States, residing at Dalton, in the county of Berkshire and State of Massachusetts, have invented new and useful Improvements in Electrically- Operated Piano-Players, of which the following is a specification.

This invention has to do with the regulation of the loudness of the tones produced by piano players in which electrically-operated playing magnets are employed for striking the piano keys, or otherwise operating the hammers, and is broadly characterized by the operation of the playing magnets by means of an electric current the strength of which is caused to pulsate or rise and fall at rapidly recurring intervals, so that the mean or efifective strength of the current during any longer interval is dependent upon such factors as the frequency of the pulsations, the limits between which their voltage varies, and the duration of the pulsations as compared with the duration of the intervals between them. These pulsations are so regulated that a current of predetermined strength is sent through each one of as many playing magnets as may be in closed circuit at one time, whether one or more, and provision is made for varying this predetermined current strength in accordance with the desired loudness of the notes to be played. In this manner the construc tion of the playing apparatus is very much simplified and its cost as well as its liability to get out of order is lessened, as compared with a piano player of the usual construction in which each playing magnet circuit is provided with a variable resistance operative for that circuit only.

Various arrangements may be employed for producing the pulsating current which energizes the playing magnets, but in the preferred embodiment of the invention, hereinafter described, some portion of the playing magnet circuit which is common to a predetermined group or series of the playing magnets has included in it a high-speed make-and-break device operated by a controller magnet the energizing circuit of which is sensitive to changes in the difference of potential between the circuit connections on opposite sides of the playing magnets, so that the strength of the current sent through the controller magnet varies with changes in the load, and the resulting variations in the operation of the make-andbreak device are such that all the playing magnets in closed circuit are supplied with a current of predetermined or normal strength. In such case the normal current strength may be varied or regulated, accordmg to the loudness of the tones desired, by varying the conditions which govern the operation of the controller magnet, and preferably provision is made for both manual and automatic regulation of this character, for reasons hereinafter explained.

The accompanying drawings illustrating he preferred form of my apparatus are mainly diagrammatic in character and include only such parts as are needful for an understanding of the invention, the various other parts and details which are com monly found in a complete apparatus of the general character under consideration being well known. In these drawings:

Figure 1 is a diagram illustrating the principal parts and circuits employed; and

Fig. 2 shows in central vertical section a make and break device hereinafter described.

The parts indicated in Fig. 1 of the drawings comprise a contact bar 2, circuit-controlling fingers 3 adapted to make contact with the bar 2 independently of one another when permitted to do so by the music sheet which controls their operation, playing magnets t arranged in parallel circuit, each in series with one of the fingers 3, a circuit wire 5 connecting the contact bar to one pole of a current generator 6, and a manual switch 7 included in the circuit wire 5 and controlling all the circuits illustrated. The parts above mentioned may be of any usual or desirable construction and are to be regarded as typical of any suitable means for controlling the circuits through a series of playing magnets according to the notes to be played thereby. The playing magnets are shown as divided in two groups corresponding respectively to the bass and treble notes of the key-board, two magnets of each group being represented, and each of these groups has a common return circuit including the current-regulating means hereinafter described. Any other desired grouping of the playing magnets may be adopted, however, and it is not necessary that they be divided into groups at all, since my currentregulating means will serve as such for any number of playing magnets. In the apparatus illustrated the parts included in the two common return circuits are identical, so that the description of one will apply as well to the other.

Referring to Fig. 1, the common return portion of thecircuit corresponding to each group of playing magnets comprises circuit wires 8 and 9 connected to the corresponding playing magnets and to the generator 6, respectively, and leading thence to contact pieces 10 separated by a gap 11. The return circuit is opened and closed at this gap by means of an electro-magnet 12, preferably of the solenoid type, the plunger 13 of which is acted upon by a spring 1& in such manner that the gap is closed whenever the magnet is deenergized or whenever the strength of the current sent through it is insufficient to overcome the force of said spring. The energizing circuit for the magnet 12 is connected across the drop, that is, it is so related to the load circuit (consisting substantially of the playing magnets) that it is affected by changes in the difference of potential between the terminals of the playing magnets, and in order that it may be sensitive to such changes said magnet 12 is wound to have a relatively high resistance, which should not be less than the resistance of one playing magnet and may be considerably greater. The energizing circuit for this magnet includes circuit wires 15 and 16, of which the wire 15 connects one end of the magnet coils with another wire 17 which leads to the contact bar 2 and is common to both of the magnets 12 illustrated in Fig. 1, while the wire 16 connects the other end of the magnet coils to the common return circuit wire 8 between the gap 11 and the playing magnets, and includes a variable resistance 18 hereinafter described. The controller magnet circuit is thus in parallel with the main or load circuit. For the purposes of regulation and adjustment it is desirable to pro vide for varying the eflect of the spring 1 1, to which end said spring may be located between the plunger 13 and a screw-threaded abutment 19 carried by a fixed support 20 and adjustable longitudinally therein.

A form of make-and-break device suitable for commercial use is shown in Fig. 2. In this form the controller magnet 12 is provided. at its ends with centrallyperforated soft-iron disks 21 and 22 connected by a soft-iron jacket 23 surrounding the magnet coils, and the soft-iron plunger 13 is so proportioned and arranged that it and the parts 21, 22 and form a magnetic circuit around the magnet coils which is practically closed except for a narrow space at the lower end of the plunger, which space varies in width according to the position of said plunger. This provides a magnet having a low inductance and exerting a concentrated stress at the space above referred to, so that the plunger is adapted to move upward and downward to a slight extent with great rapidity, in correspondence with the .fiuctuations in the current sent through the mag net. The plunger 13 carries a metallic tip 21 which is insulated from the plunger by a suitable bushing 25 and is preferably provided at its upper end with a flat disk of some infusible metal, such as platinrun, which corresponds to one of the contact pieces 10 shown in Fig. 1 and is therefore marked 10 in Fig. 2. The other contact piece is represented in Fig. 2 by another flat platinum disk 1O located directly over the plunger 13 and secured to the lower end of a rod 27 carried by an overhanging arm 28 of a supporting bracket 29 to which the magnet 12 is fixed, said rod 27 being made capable of vertical adjustn'ient by passing it through a block 30 and providing it and the block with engaging screw threads, as shown. The rod 27 is insulated from the bracket 29 by means of a suitable bushing 31 surrounding the block 30 and is connected to the circuit wire 5), while the tip 21 is connected to the circuit wire 8, so that the gap indicated at 11 in Fig. 1 is provided for in Fig. 2 by the separation of the platinum disks carried by the plunger 13 and the rod 27 respectively. The spring 32, which corresponds to the spring ll in Fig. 1 and is shown as surrounding the jacket 23 and located between a fixed support 33 and a plate 31 secured to the upper portion of the plunger 18, acts to elevate said plunger and hold the two platinum disks in contact with each other whenever the magnet 12 is deenergized or exerts a pull which is insufiicient to overcome the pressure of the spring 32, which pressure can be regulated by adjusting the rod 27 upward or downward to vary the contact position of the platinum disks.

The parts above described serve the purpose of transmitting the necessary current through such of the playing magnets in one group as are in closed circuit at any given time, and the manner in which this is llone will now be explained. So long as the switch 7 is open no current can pass through any of the circuits illustrated, and hence the magnet 12 is decnergized and .its springoperated plunger 13 closes the gap in the common return circuit. It now the switch 7 is closed but no playing magnet is in closed circuit the circuit through the magnet 12 is closed by way of the wire 5, contact bar 2, wires 17, 15, 1(3 and the common return wires 8 and 9, and the energizing of this magnet innnediately results in drawing its plunger 13 into the magnet and thus opening the gap. Fig. 1 shows the parts in this position. Thereby the circuit through the magnet 12 is immediately broken and the gap is closed again, and so on, the result being that a very rapid vibration of the plunger 13 is set up which causes a pulsating current to be supplied to the magnet 12. Since this magnet and its circuit connections constitute the only load in the circuit the pulsations of current are produced by the full voltage developed by the generator 6, so that the plunger 13 is drawn into the magnet 12 so far that the intervals between successive contacts at the gap are relatively long and the intervals of contact are relatively short, only enough current being transmitted to operate the plunger 13. If new the circuit through a playing mag net in the corresponding group is closed, thus throwing a load into the main circuit between the terminals of the controller magnet circuit, the difference of potential between these terminals drops somewhat and therefore the strength of the pulsations of current sent through the controller magnet is diminished, with the result that the plunger 13 is not drawn into the magnet so far as before. Consequently, the duration of contacts at the gap is longer and the contacts occur more frequently, the intervals between contacts are shorter, and the current necessary for operating the playing magnet is transmitted through the same. If two or more playing magnets are thrown into circuit at the same time the current which passes through the controller magnet is diminished still further and said magnet be comes correspondingly weaker, the increased current required being transmitted by the greater frequency and duration of the successive contacts at the gap. Thus by properly calibrating and adjusting the controller magnet and the parts associated with it said magnet and associated parts may be caused to automatically transmit a current of predetermined strength through any number of the playing magnets, within the capacity of the generator. The contact pieces 10 and 10 are purposely given considerable area in order that they may interpose no appreciable resistance at their point of contact and also in order to avoid over-heating at this point. Hence the playing magnets furnish practically the entire resistance in the main circuit, and therefore the same current is transmitted through each one of as many of them as are in closed circuit at one time, since each magnet receives full voltage when ever the gap at the contact pieces is closed.

Since the striking of a note by a playing magnet is accomplished in a small fraction of a second, (about .01 of a second for a very loud note and about .1 of a second for a very soft note,) it will be evident that the plunger 13 must vibrate with great rapidity if a number of current pulsations are to be transmitted during the striking of a note.

Its rate of vibration will vary somewhat, being increased when the current sent through the controller magnet is weakened and diminished when said current is strengthened, but satisfactory results will be obtained if the mean rate of vibration 1s about one hundred per second. This gives about ten pulsations of current during the striking of a very soft note, and since the striking of a very loud note requires the full current strength, the gap will be kept closed, or practically so, while such a note is being struck.

lVhile the parts above described will operate effectively in the manner already eX- plained, in practice I prefer to add thereto a resistance (shown at in Fig. 2) which bridges the gap produced by the operation of the make and break device, the function of this resistance being to transmit a certain amount of current regardless of the opening and closing of the gap. The employment of this resistance results in keeping the playing magnets and the controller magnet energized to a certain extent during the intervals between the successive contacts at the gap, and thus steadies these magnets and prevents the pulsations in the playing magnets from producing tremulous effects in soft notes struck by the piano keys. It also lessens the spark at the gap when the circuit is opened at this point. Preferably the effect of the resistance 35 is such that it will pass just enough current to strike the softest note required when a single playing magnet is in closed circuit, and in such case the controller magnet is so constructed that its previously-described operation is modified as follows: WVhen the circuit through the wire 5 is closed at the switch 7, the resistance 35 transmits enough current through the controller magnet circuit to keep said magnet energized to such an extent that the gap 11 is not closed at all, and if the expression-producing means hereinafter described are so adjusted as to cause the apparatus to strike the softest notes required said gap is not closed when a single playing magnet is thrown into circuit, but if a louder tone is required or if two or more playing magnets are thrown into circuit simultaneously, then the current sent through the controller magnet is weakened sufficiently to cause the opening and closing of the circuit at the gap 11 as previously described, the pulsations thereby transmitted being superimposed upon the continuous current which passes through the resistance 35.

Since the pulsations transmitted by the action of the controller magnet will vary with the pressure exerted by the spring 32 on the plunger 13, the effective current supplied to the playing magnets may be regulated by varying the effect of said spring, as by adjusting the rod 27 upward or downward. This adjustment is useful for adapt ing the apparatus to different piano actions, some of which are stilier than others and therefore require more force to be applied to the keys in order to strike notes of a given loudness, while for regulating the general loudness of the tones produced during the playing of a composition I employ the variable resistance 18. According to Fig. 1 this resistance is divided into a number of portions each connected to a corresponding metallic terminal 36, these terminals being so arranged that a cont-act finger 37 can be moved into contact with them successively. Said finger is connected by a flexible wire 38 to the circuit wire 16, and hence the amount of the resistance 18 which is included in the controller magnet circuit will depend upon the position of the finger 37, which may be moved along the segments by any suitable means. The eli'ect of such movement will evidently be to vary the strength of the current sent through the controller magnet, independently of the operation of the other parts of the apparatus, and any such variation in the strength of the controller magnet current will produce its appropriate eiiect on the transmission of the current pulsations sent through the playing magnets and therefore on the loudness of the notes struck thereby.

As another ay of varying the loudness of the notes struck a portion of the resistance 18 may be thrown into and out of circuit by means controlled by a special circuit. For example, in Fig. 1 is shown an arrange ment of this character comprising circuit wires 39 and 4L0 leading from dii'l'erent portions of the resistance 18 to opposite sides of a gap which is normally closed by a. metallic contact piece 11 carried by the plunger 1-2 of a solenoid 13 and arranged to open the gap against the pressure of a spring 4% whenever the solenoid 4,3 is energized. This solenoid is included in a circuit comprising on one side wires and i6 leading to the common return circuit of the playing magnets and on the other side a wire 47 leading to a special circuit-controlling finger 48 under the control of the music sheet at the contact bar 2. So much of the resistance 18 as is included between the wires 39 and 40 is thus short-circuited so long as the circuit controlled by the finger 48 is open, but is thrown into the controller magnet circuit whenever the solenoid 4:3 is energized and thus weakens the current sent through said controller magnet and causes louder tones to be produced. This arrangement is well. adapted for producing sudden and considerable variations in loudness and hence is useitul for accenting purposes it controlled by the music sheet in the manner shown and described in my prior United States Patent No. 1,058,902, granted on the 15th day of April, 1913. In practice a portion of the resistance 18 is employed for producing partial or moderate accent, as just described, while the remainder of the resistance is used for general regulation of the loudness of the tones through the operation of the finger 37.

Instead of the partial accent produced by the operation of the solenoid 13-3 and associated parts, so-called total accent may be secured in various ways, as for example, by keeping the gap 11 closed during the striking of the note or notes to be accented. In the arrangement shown in Fig. 1 this is accomplished by including in some convenient portion of the controller magnet circuit, as in the wire 16, for example, a gap which is normally closed by a metallic contact piece 4:9 carried by the plunger 50 of a solenoid 51, this solenoid being included in a circuit comprising on one side a wire leading to the wire 46 and on the other side a wire leading to a special circuit-controlling finger 51 at the contact bar. A spring 55 holds the contact piece st!) in position to close its gap and thus con'iplete the circuit through the controller magnet whenever the circuit through the solenoid 51 is open, but whenever the latter circuit is closed by the operation of the finger 54 the contact piece 19 opens its gap and thus breaks the controller magnet circuit, whereupon the common return circuit is closed at the gap 11 and transmits the full current until. the controller magnet is energized again. It will be obvious that the gaps at the contact pieces 11 and 19 may be opened manually, if desired.

So far as I am aware, I am the first to produce an clectrically-operated piano player in which the playing magnets are operated by a pulsating current during the striking of a note and the effective strength of the current is varied by *arying the pulsations, and hence I do not consider my invention to be limited to the apparatus herein specifically described, since many changes may be made in the same and in the various parts thereof without departing from the broadly new characteristics involved therein.

I claim 1. An electrically-operated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played thereby, and means for producing a pulsating current in the same during the striking of a note.

2. An electrically-operated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played. thereby, means for producing pulsations of current in the same during the striking of a note, and means for varying the pulsations and thereby varying the strength of the current.

3. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a gap therein, in ans for closing the branch circuits through the several magnets according to the notes to be played thereby, and means for rapidly opening and closing the gap in the energizing circuit during the striking of a note and thereby producing a pulsating current therein.

4. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, means for rapidly opening and closing the gap in the energizing circuit and thereby producing a pulsating current therein, and a resistance bridging said gap.

5. An electrically-operated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played thereby, and means responsive to changes in the load for producing a pulsating current in said energizing circuit.

6. An electrically-operated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a supplementary circuit in parallel with the playing magnets, and means controlled by said supplementary circuit for producing a pulsating current in said energizing circuit.

7. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing CHCLHC having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, and means responsive to changes in the load for rapidly opening and closing the gap in the energizing circuit and thereby pulsating the current therein.

8. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, means responsive to changes in the load rapidly opening and closing the gap in the energizing circuit and thereby pulsating the current therein, and a resistance bridging said gap.

9. An electrically-operated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor,

means for closing the branch circuits through the several magnets according to the notes to be played thereby, a supplementary circuit in parallel with the playing magnets, a controller magnet in the supplementary circuit, and means operated by the controller magnet for producing a pulsating current in said energizing circuit.

10. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a supplementary circuit in parallel With the playing magnets, a controller magnet in the supplementary circuit, and means operated by the controller magnet for rapidly opening and closing the gap in said energizing circuit.

11. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a supplementary circuit in parallel with the playing magnets, a controller magnet in the supplementary circuit, means operated by the controller magnet for rapidly opening and closing the gap in said energizing circuit, and a resistance bridging said gap.

12. An electrically-operated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a controller magnet and means operated thereby for producing a pulsating current in the energizing circuit, and means for varying the strength of the current sent through the controller magnet.

13. An electrically-operated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a controller magnet and means operated thereby for producing a pulsating current in the energizing circuit, a variable resistance in circuit with the controller magnet, and means for varying said resistance.

14. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a supplementary circuit in parallel with the playing magnets, a controller magnet and a variable resistance included in said supplementary circuit, means for varying said resistance, and means operated by the cum troller magnet for rapidly opening and closing the gap in the energizing circuit and thereby pulsating the current therein.

15. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a supplementary circuit in parallel with the playing magnets, a controller magnet and a variable resistance included in said supplementary circuit, means for varying said resistance, means operated by the controller magnet for rapidly opening and closing the gap in the energizing circuit and thereby pulsating the current therein, and a resist ance bridging said gap.

16. An electricallyoperated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played thereby, means including a controller magnet for producing a pulsating current in the energizing circuit, a resistance in circuit with the controller magnet, and means for opening and closing a shunt circuit around a portion of said resistance.

17. An electricallyoperated piano player comprising playing magnets" arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played thereby, means including a controller magnet for producing a pulsating current in the energizing circuit, a variable resistance in circuit with the controller magnet, means for opening and closing a shunt circuit around a portion of said resistance, and means for varying said resistance independently of the latter circuit.

18. An electrically-operated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played thereby, means including a controller magnet for producing a pulsating current in the energizing circuit, a resistance in circuit with the controller magnet, and means comprising a special circuit and an electro-magnet therein for opening and closing a shunt circuit around a portion of said resistance.

' 19. An electrically-operated piano player comprising playing magnets arranged in parallel, an energizing circuit therefor, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a supple mentary circuit in parallel with the playing magnets, a controller magnet and a variable resistance included therein, means operated by the controller magnet for producing a pulsating current in the energizing circuit, and means for opening and closing a shunt circuit around a portion of said resistance.

20. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a. gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, means for rapidly opening and closing the gap in the energizing circuit and thereby pulsating the current therein, and means for temporarily preventing the opening of said energizing circult.

21. An electrically-operated piano player comprising playing magnets arranged in parallel. branches of an energizing circuit having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, means for rapidly opening and closing the gap in the energizing circuit and thereby pulsating the current therein, and means including a special circuit and an electroinagnet therein for temporarily preventing the opening of said energizing circuit.

22. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a supplementary circuit in parallel with the playing magnets, a controller magnet in.- cluded in the supplementary circuit, means operated by the controller magnet for rapidly opening and closing the gap in the energizing circuit, and means for opening said supplementary circuit.

23. An electrically-operated piano player comprising playing magnets arranged in parallel branches of an energizing circuit having a gap therein, means for closing the branch circuits through the several magnets according to the notes to be played thereby, a. branch circuit in parallel with the playing magnets, a controllermagnet included in the latter branch circuit, means operated by the controller magnet for rapidly opening and closing the gap in the energizing circuit, and means comprising an additional circuit and an electro-magnet therein for opening the controller-magnet circuit.

In testimony whereof, I have hereunto subscribed my name this twenty-seventh day of May, 1913.

WALTER C. REED. Witnesses E. D. CHADWIGK, Josnm-r T. BRENNAN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of latents, Washington, I). C. 

